Britain has blamed the attempted assassination, which also resulted in the hospitalisation of Skripal’s daughter Yulia and an English police officer, on Russia.

Skripal worked for Russian military intelligence before becoming a double agent and helping Britain, and was arrested by Russia in 2004. He was subsequently traded with the UK in a spy swap, and now lives in Salisbury, England – the site of the attack.

According to The New York Times, Skripal provided these briefings to spies in Estonia and the Czech Republic.

Discussing the briefings, a retired Czech spy told The Guardian: “The ties between MI6 and the Czech intelligence services are so good that it’s normal that the British were willing to rent him out, so to speak, to the Czech services. It would have been a very useful and interesting meeting for the Czechs, there’s no doubt about that. When do you have the chance to meet a KGB or GRU officer? Almost never.”

It’s not clear, however, if Skripal’s actions informed Russia’s attempt on his life: Both The New York Times and The Guardian cite security sources who say that these briefings, by themselves, wouldn’t necessarily be reason to carry out such a risky assassination attempt – especially as Skripal’s intelligence will be outdated. “If he was pitching other Russians, that would put him higher on the list,” one source told The Times. “Or if he got too close to something that was really sensitive to the Russians.”